1. Field of the Invention
The invention relates to a gas generator for an airbag, used in an airbag system installed in a vehicle to release a gas for inflating the airbag in the event of a collision, and preferably relates to a gas generator for an airbag, which is used in an airbag system for developing an airbag over the lateral side of a vehicle occupant.
2. Description of the Related Art
As gas generators for air bags installed in automobiles and other vehicles, various types of gas generators such as for a driver side air bag, for a front passenger side air bag, for a side air bag, for a curtain air bag or for a pretensioner has been provided, suitable to installation locations, purposes and so forth.
Among them, a gas generator used for a side airbag serves to inflate an airbag that provides protection against an impact from the lateral side of an occupant, which improves safety in the event of a lateral collision of the vehicle, for instance, and in most cases, is installed in a seat back, a B-pillar (the center pillar), or the like.
In particular, in the case of a side airbag gas generator or other small gas generator, in order to ensure enough installation space, or to reduce the weight of the gas generator itself, a pyrotechnic gas generator, which uses a solid gas generating agent, have been used as the gas generation source for inflating the bag. In such a gas generator, the gas for inflating the airbag is produced by combustion of the solid gas generating agent serving as the gas generation source. This gas is very hot and combustion by-products are also produced during the combustion, and therefore, a filter is generally used for purifying and cooling the gas produced by combustion. Even in this case, the problem of ensuring enough installion space in the vehicle has to be solved, and the purification and cooling efficiency has to be enhanced. Furthermore, in case of a gas generator for a side airbag, the airbag has to be inflated more quickly because there is less space between the occupant and the structural members inside the vehicle. Accordingly, a filter used for such a gas generator needs to be as little an obstacle as possible in the release of the gas.
In addition, the structure of the gas generator itself needs to be simple in order to avoid difficulty in the manufacture of the gas generator and to eliminate problems that would otherwise be caused by a complicated structure, for example.
A conventional gas generator for a side air bag is disclosed in U.S. Pat. No. 5,542,702, for example.
Also, a gas generator using a filter is disclosed in U.S. Pat. No. 4,005,768, for example.